The invention relates to a process for adapting the position of printing plates to the deformation (fan-out) of the paper to be printed through mositure and ink absorption on passing between several successive pairs of printing rolls and/or for adaptation to deformations occuring at the fixing device of a printing roll and resultant changes in the position of a printing plate, whereby when the printing plate is produced it is provided with marks for positionally accurate stamping and/or bending and is inserted therewith into a stamping and/or bending machine and is adjusted and aligned therein according to the marks.
The invention also relates to a device for carrying out this process with a stamping and/or bending machine for applying the stamping for the register pins of printing rolls on printing plates and/or for bending for mounting the respective printing plate on the printing roll.
It is known from EP-A-0 229 892 that, particularly in color printing, as the the paper to be printed passes through several pairs of printing rolls it increases or possibly even decreases in its width oriented crosswise to the feed, depending on how much moisture is thereby absorbed and on what structure the paper has. Among experts this phenomenon is called "fan-out".
Particularly when producing color prints, one color may as a result become displaced relative to another one or relative to the printing area proper, which leads to a muddy and unsatisfactory print and is accepted at best for cheap printed works.
For remedy the EP-A-0 229 892 describes that such dimensional changes occuring in the paper web be corrected by adjusting the register pins for the printing plates on the printing rolls, i.e. in a structurally complex manner the register pins must be provided so as also to be adjustable. In the course of a great number of specimen prints, the printer has to adjust the register pins in such a way that for the respective grade of paper the paper web error occuring is corrected for the printing to be carried out.
If, however, a different grade of paper is then printed with the same printing machine, the correction has to be repeated because this other paper has a different fan-out. This is not only time-consuming and difficult, requiring very great experience, but is nevertheless still fraught with errors.